Japanese Patent Laying-Open No. 2-266855 discloses a starter-generator attaining a function as a three-phase motor starting an engine mounted on a vehicle and a function as a three-phase AC generator charging a battery.
Referring to FIG. 9, a starter-generator 300 disclosed in Japanese Patent Laying-Open No. 2-266855 includes a motor unit 301 and a drive unit 302. Motor unit 301 includes a stator and a rotor. Drive unit 302 is provided on an end surface 301A of motor unit 301. Drive unit 302 includes a cylindrical member 302A and a power module 302B. Power module 302B is formed on a surface of cylindrical member 302A. That is, power module 302B is arranged in a direction perpendicular to a radial direction 303 of cylindrical member 302A and in a longitudinal direction 304 of a rotation shaft 301B of motor unit 301.
Power module 302B feeds a current to a coil included in motor unit 301 and drives motor unit 301 so that the rotor outputs a prescribed torque. When the rotor in motor unit 301 rotates by rotation power of an engine, an AC voltage induced in three stators is converted to a DC voltage, whereby a battery is charged.
In this manner, power module 302B is provided on end surface 301A of motor unit 301, and drives motor unit 301 as a motor or a generator.
In the conventional starter-generator, however, the power module is arranged in a direction perpendicular to a radial direction when the rotation shaft is assumed as a center and in a longitudinal direction of the rotation shaft. Accordingly, it is difficult to achieve smaller size of the starter-generator.
In particular, when a control circuit to control a generator installed in an engine is incorporated in the generator, a similar problem tends to arise.
As Japanese Patent Laying-Open No. 2-266855 does not clearly disclose a position where an electrode included in the power module is arranged, it is difficult to enhance efficiency in cooling the power module in the conventional starter-generator.
In addition, as Japanese Patent Laying-Open No. 2-266855 does not clearly disclose a position where a wire to the power module is arranged either, it is difficult to achieve shorter length and simplification of the wires in the conventional starter-generator.